Vacuum tube



July 27, 1948. M. D. BALLER VACUUM TUBE Filed June 19, 1945 INVENTOR.

' MELVIN 0. BALLER Patented July 27, 1948 UNI-TED S TAT ES PATENT OF Fl CE VACUUM TUBE Melvin D. Baller, Little Silver, N..J..

Application June 19, 1943, Serial'No. 491,466

Claims.

The. invention described herein may be manufacturedi and; used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This: invention relates to vacuum tubes, and more particularly to transmitter tubes intended for pulseecho' work.

The primary object of the present invention is to generally improve vacuum tubes, and more particularly, to provide a vacuum tube especially designed and adapted to meet the unusual requirements ofpulse transmission work for pulse echo or radar systems. For that purpose a large. cathode emission is required, but only in short pulses. The peak power is extraordinarily large, yet the average power may be moderate or even. low.

I accordance with the present invention, the cathode, grid, and anode are arranged coaxially, but with the cathode at the outside instead of at the center, and with the anode at the center instead of at the outside. In this way the oathode area is. increased, thus making possible greater cathode. emission. The decrease in heat dissipation from the smaller anode is permissible because; of the-intermittent operation, which provides time between pulses for heat dissipation, or, expressed difierently, because of the low average power being dissipated.

Other objects of the invention center about the physical structure of the tube and the support ofthe tube electrodes, and are to provide lead-ins which, inimize discontinuity of the radio-ireqllency path; which provide large-area, lowresistance conductors; and which pass through the tube envelope at remotely spaced points in order to minimize inter-lead-in capacitance.

To accomplish the foregoing and such other objects: as; hereinafter appear, my invention resides in the vacuum tube elements and their relation one to another, as hereinafter are more particularly described in the specification and sought to be defined in the claims. The specification is accompanied by a drawing in which Figure l a longitudinal section through a vacuum tube embodying features of my invention Figure 2 is a simplified schematic showing or the same; and

Figure.- 3- is a. transverse section taken. approximately in the plane of the line 3-3 of Figure 1.

Referring to. the drawing, the vacuum tube comprises an anode. [-2, a grid I4 surrounding the anode, and a cathode lfisurrounding the grid. It will be evident that with this inverted construction, the electron-emitting area of the oathode is increased.

The electrodes are most simply made cylindrical in configuration, and are disposedcoaxially relative to one another. Thecathode la is: preferably oxide-coated on the inside, andisprovided with a heater filament It on the outside.

The anode i2. is. supported by an anode lead-in 2t.- extending from the. anode: through one wall 22 of the envelope 24 of the tube. The. grid. is supported by a grid lead-in 26 extending in opposite direction. through. the opposite wall 28. of the envelope. Additional conductive means 30 extend. from the cathode transversely through the envelope 24.. In this way the lead-insv of the electrodes are spaced remotely from one: another with aminimumot inter-lead-in capacitance.

Considering the structure in greater detail, the anodelead-in. 20. is preferably a large diameter tubular continuation of the anode l2, and the grid lead-in 28. also. is preferably a, large diameter pipe having approximately the same diameter as the grid or anode. The. main body of the envelope. 2.4. is. cylindrical, and preferably comprises cylindrical glass. walls. 32 and 34 in which the jacent ends of said walls being sealed to theopposite flat faces of the annulus. The cathode I 5 is secured to the inside portion 35 of annulus 3ft, while the outside portion 38- serves for external connection to the. cathode of the tube. The ends of the envelope are preferably metal disks, which may be inwardly flanged, the edges of the flanges being feathered or tapered as shown at All, the resulting tapered edges being embedded the ends' of the cylindrical glass en-ve lope. The. thickness of these metal ends has been exaggerated in the drawing. The tubular lead-ins 25!. and 2 6 are welded to the ends 22 and. 28.

The cathode IB ispreferably a cylindrical metal can provided with a layer of refractory insulation 42 on which the heater filament wire [8 may be wound. If desired. the ends of the cathode. may be flanged outwardly as shown at 44, 46, to receive a cylindrical jacket 48, which is slid thereover to protect the heater filament and to direct its heat toward the cathode. The end flange 46 is welded to a ring 50, which in turn is secured to the annulus 38, as by means of screws 52.

The grid M, in the present case, is made up of a cage of grid wires 54 welded at one end to a disk 56, and at their opposite end to a ring 58. The disc 56 is welded to the inner end of leadin 26.

One end of the heater filament is connected to a lead-in 60, sealed in a glass stem 62. The other end of the heater filament may be connected to the cathode, in which case the heater circuit is completed thru the annulus 30. The anode 6'2 is closed at its inner end by a disk 64, and the disks 56 and 64 are both sealed to their respective lead-ins with a vacuum-tight seal, thus making it possible to leave the outer ends of the lead-ins open, as shown.

It is believed that the construction of my improved vacuum tube, as well as the advantages thereof, will be apparent from the foregoing detailed description. The large-area cathode provides maximum peak emission during the transmission pulses, while even the smaller-area enclosed anode is capable of dissipating the relatively low average power. The large-diameter straight tubular lead-ins of the anode and grid provide an efiicient radio-frequency path with minimum discontinuity. All of the lead-ins pass through the envelope at remotely spaced points, thereby minimizing inter-lead-in capacitance.

It will be apparent that while I have shown and described my invention in a preferred form, changes and modification-s may be made in the structure disclosed, without departing from the spirit of the invention, as sought to be defined in the following claims.

I claim:

1. A vacuum tube comprising a generally cylindrical glass envelope closed by metal ends, said envelope housin an electrode assembly comprising cylindrical anode, grid, and cathode electrodes disposed coaxially of the envelope with the anode at the center and the cathode at the outside, the anode being supported by an anode lead-in extending from said anode through one of the metal ends of the envelope, and a grid lead-in extending from the grid in opposite direction through the opposite metal end of the envelope, and means supporting the cathode including a metal annulus disposed transversely of the envelope and dividing the aforesaid cylindrical glass envelope into two portions the adjacent ends of which are sealed to the opposite faces of the annulus, said cathode being secured to the inside portion of the annulus, and the outside portion of the annulus constituting an external connection for the cathode.

2. A vacuum tube comprising a generally cylindrical glass envelope closed by metal ends, said envelope housing an electrode assembly comprising cylindrical anode, grid, and cathode electrodes disposed coaxially of the envelope with the anode at the center and the cathode at the outside, the anode being supported by an anode leadin consisting of a large diameter tubular continuation of the anode extending from said anode through one of the metal ends of the envelope, and a grid lead-in consisting of a large diameter pipe having approximately the same diameter as the grid and extending from the grid in opposite direction through the opposite metal end of the envelope, and means supporting the cathode ineluding a metal annulus disposed transversely of the envelope and dividing the aforesaid cylindrlcal glass envelope into two portions the adjacent ends of which are sealed to the opposite faces of the annulus, said cathode bein secured to the inside portion of the annulus, and the outside portion of the annulus constituting an external connection for the cathode.

3. A vacuum tube comprising a generally cylindrical evacuated glass envelope closed by cupshaped metal ends, the edges of the cup-shaped ends being tapered and embedded in the ends of the glass cylinder sealing the parts together, said envelope housing an electrode assembly comprisin cylindrical anode, grid, and cathode elec trodes disposed coaxially of the envelope with the anode at the center and the cathode at the outside, the anode being supported by an anode leadin consisting of a large diameter tubular continuation of the anode extending from said anode through one of the metal ends of the envelope, and a grid lead-in consisting of a large diameter pipe having approximately the same diameter as the grid and extending from the grid in opposite direction through the opposite metal end of the envelope, and means supporting the cathode.

4. A vacuum tube comprising a generally cylindrical evacuated glass envelope closed by cupshaped metal ends, the edges of the cup-shaped ends being tapered and embedded in the ends of the glass cylinder sealing the parts together, said envelope housing an electrode assembly comprising cylindrical anode, grid, and cathode electrodes disposed coaxially of the envelope with the anode at the center and the cathode at the outside, the anode being supported by an anode leadin consisting of a large diameter tubular continuation of the anode extending from said anode through one of the metal ends of the envelope, and a grid lead-in consisting of a large diameter pipe having approximately the same diameter as the grid and extending from the grid in opposite direction through the opposite metal end of the envelope, and means supporting the cathode, including a metal annulus disposed transversely of the envelope and dividing the aforesaid cylindrical glass envelope into two portions the adjacent ends of which are sealed to the opposite faces of the annulus, said cathode being secured to the inside portion of the annulus, the outside portion of the annulus constituting an external connection for the cathode, the inside of said cathode being oxide-coated, and the outside of said cathode being provided with a heater filament for heating the same,

' 5. An electronic tube comprising a tubular glass envelope closed by annular metal ends, the outer edges of the annular ends being sealed to the ends respectively of the tubular envelope, said envelope housing an electrode assembly comprising cylindrical anode, grid and cathode electrodes disposed substantially eoaxially of the tubular envelope with the grid surrounding the anode and the cathode surrounding the grid, the anode being supported by an anode lead-in consistin of a tubular continuation of the anode having approximately the same diameter as the anode and extending from said anode through one of the metal ends aforesaid, and the grid being supported by a grid lead-in consisting of a tubular continuation of the grid having approximately the same diameter as the grid and extending from the grid in opposite direction through the opposite metal end aforesaid, and means supporting the cathode, and a lead-in therefor spaced from 5 the anode lead-in and grid lead-in, the interiors Number of the anode, anode lead-in and the grid lead-in 1,957,423 being exposed to the circumambient atmosphere. 2,018,314 MELVIN D. BALLER. 2,091,443 5 2,190,668 REFERENCES CITED 2 21 1 0 The following references are of record in the file of this patent:

Number UNITED STATES PATENTS 1. 229,019

Number Name Date 1,851,440 MeIlvaine Mar. 29, 1932 1,871,357 Brace Aug. 9, 1932 Name Date Freeman May 1, 1934 Nyman Oct. 22, 1935 Heintz Aug. 31, 1937 Llewellyn Feb. 20, 1940 George Oct. 1, 1940 FOREIGN PATENTS Country Date Great Britain Feb. 19, 1925 Great Britain Apr. 6, 1926 Great Britain Oct. 1, 1928 

